This invention relates generally to recirculating document feeders, and more particularly to a recirculating document feeder for use with an electrophotographic apparatus for producing pre-collated or post-collated simplex or duplex copies from simplex or duplex original documents.
Electrographic reproduction apparatus typically produce copies of original information on receiver members, such as cut sheets of plain bond paper for example. Such information copies may be formed on one side of the paper sheets (referred to as simplex copies), or on both sides of such sheets (referred to as duplex copies). In certain commercial reproduction apparatus capable of producing duplex copies, selected information is electrographically reproduced sequentially on the first sides of sheets which are thereafter collected in an intermediate tray. Such sheets are then sequentially transported from the intermediate tray back through the apparatus to have selected information respectively reproduced electrographically on the second sides of such sheets. This reproduction procedure is generally referred to as "two-pass" copying.
In a reproduction apparatus capable of making simplex copies or "two-pass" duplex copies from simplex or duplex document sheets, such apparatus typically requires a complex document sheet feeder, such as shown for example in U.S. Pat. No. 4,229,101, issued Oct. 21, 1980, in the name of Hamlin et al. The complexity of the feeder arises from the fact that in reproducing information from a multi-sheet document, handling of the document sheets requires complex logic in that all sheets bearing even side information must be reproduced and collected before all sheets bearing odd side information are reproduced (or vice-versa). Moreover, when the multi-sheet document is of the duplex variety, the sheets must at some time be turned over to enable reproduction of information on both sides thereof.